Role of H2O2 in the photo-transformation of phenol in artificial and natural seawater

► Hydrogen peroxide-mediated solar-driven transformations of pollutant in seawater are studied. ► In seawater, a photo-Fenton rather than a the Fenton reaction takes place. ► A key role is played by iron(III) species. ► The addition of increasing concentrations of H2O2 hinders the formation of halophenols.